Diffusion of intrinsic localised modes by attractor hopping

Propagating intrinsic localised modes (discrete breathers) exist in the dissipative driven sine-Gordon chain as attractors of the dynamics. Thermal fluctuations induce random transitions between attracting configurations corresponding to opposite signs of the propagation velocity, effecting a diffusive motion of the breather. Results for the mean value and the variance of the position from numerical simulations (Heun method) are compared with predictions from a two-parameter model developed in this paper.